Water pollution by mankind is one of the most pressing social and economic problems of our time. Because man irresponsibly discharges great quantities of liquid and solid pollutants into the environment, including river and water bodies, and has thereby disturbed the equilibrium of the ecosystem of the planet, many rivers, lakes and seas no longer have the ability to purify themselves. A main source of water pollution is deleterious sludge or solids contained in sewage and industrial waste.
Throughout the world, industry and governments are increasingly confronted with the challenge and expense of providing modern waste water facilities that meet public demand and enacting stringent regulatory requirements necessary to produce a cleaner environment. In Canada, less than half of all municipal communities have adequate waste water facilities Globally, the need for economic, environmentally friendly sewage and industrial waste water treatment is rapidly approaching a crisis point.
There is a pressing need for a modern, efficient and economical method and apparatus for treating sludge or solids from municipal and industrial wastes to yield clear, liquid effluent (supernatant) which can be readily disposed of, reused or recycled, and solid components which can be broken down into compost and or other environmentally acceptable solids.
A number of purported solutions have been developed over the years for treating effluents of various types. A number of patents which are pertinent to this field of technology have been issued by the U.S. Patent and Trademark Office.
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 3,045,984 Cochran July, 1962 3,886,073 Briltz May, 1975 3,965,975 Edmundson June, 1976 4,142,970 von Hagel et al. March, 1979 4,164,470 Briltz August, 1979 4,192,746 Arvanitakis March, 1980 4,260,488 Condolios April, 1981 4,710,290 Briltz December, 1987 4,834,878 Anderson May, 1989 4,830,736 Sander et al. June, 1989 ______________________________________
More recently, U.S. Pat. No. 5,124,035, granted Jun. 23, 1992, Dunne et al., has issued for an invention entitled "Apparatus for Treatment of Effluent". That U.S. patent discloses and claims a system for treating effluents such as sewage. The system includes a mixing chamber and a separation chamber. In the mixing chamber, various chemical additives are introduced into the effluent and mixed to create a flocculent. The flocculated solid materials are separated in the separating chamber. The mixing chamber, which is in the form of a long tube, contains a plurality of perforated transverse baffles which are spaced longitudinally in a helical pattern relative to the longitudinal axis of the tube. Each baffle has tapered holes therein to act as a venturi to mix the materials. In the separating chamber, the mixed materials are caused to flow longitudinally in a purported laminar flow condition to allow stratification between the liquid and the solid materials. The separation chamber contains an auger flight rotates slowly. The flight has holes therein which thus purportedly generate a laminar flow. This is said to provide improved separation of the solid and the liquid components.
A prototype of the Dunne et al. system disclosed and claimed in U.S. Pat. No. 5,124,035, has been tested experimentally and has been found to have some serious shortcomings. One is that the grit in the sewage effluent collects on the baffles in the mixing tube over time. Typical sewage contains a large variety of solids including faeces, condoms, tampons, sanitary napkins, disposable diapers, coffee grounds, tea bags, coffee filters, rags, ground bones, dirt from laundry facilities, sweepings, vacuum cleaner solids, detergent, fibres from various textile sources, hair, fruit and vegetable peelings, garburator refuse, and numerous other types of household and industrial solids. The coffee grounds, dirt, peelings, fibres, and other solid materials that do not lend themselves readily to flocculation and are collectively termed "grit", quickly collect on the baffles and plug the holes in the baffles. This interferes with the operation of the mixing chamber. Before long, the mixing tube has to be opened and the baffles removed for cleaning. Another problem is that adding the chemicals at one or more locations along the length of the tube does not yield optimum mixing of the chemicals with the solids.